Field of the Invention
The present invention relates to a method and apparatus for inspecting a flat panel display (FPD), and more particularly, to a method and apparatus for optically inspecting an FPD in a reduced time.
Description of the Related Art
The development of information and communications technology and the diverse needs of the information society are increasing the demand for displays. Cathode ray tubes (CRTs), which were once the most common type of display devices, are being replaced with flat panel displays (FPDs) to meet the demand for more compact and less power-consuming display devices. Some of the most widely used FPDs include electroluminescent displays (ELDs), liquid crystal displays (LCDs) (TFT-LCDs, TN/STN), plasma display panels, and organic electroluminescent displays.
To maintain stable quality of an FPD, it is important to develop materials and processes. However, it is also important to remove defects in a panel (such as glass or plastic) used for the fabrication of the FPD.
In a conventional method of inspecting an FPD to find any defects, light is irradiated onto the panel surface, and defects in the panel surface are detected based on optical changes of the irradiated light. That is, light emitted from a light source reaches the FPD (i.e., a subject) after passing sequentially through a mirror, a lens, a liquid crystal plate, etc. Then, an inspector may determine the presence or absence of defects such as scratches or stains. However, if the luminance of the light is not stable, it may be impossible to accurately determine the presence or absence of defects due to the non-uniform brightness of the FPD.
Also, a method of automatically inspecting an FPD using a camera may be used to find any defects. However, if an image of the FPD is photographed and analyzed by the camera, a lot of time may be required to inspect the FPD.